The present invention relates to phonocardiograms and in particular to an improved technique for taking spectral phonocardiograms.
The prior art has noted the potential utility of computer-based Fourier analysis of heart sounds for diagnostic purposes. However, the meager amount of previous experimental work that has been done in this area has largely been limited to average studies of first (S1) and second (S2) heart sound spectra for normal individuals. Typically, such studies have been restricted to frequencies below about 150 Hz and the utility of the approach has been severely limited by the long computing time required for Fourier analysis. In addition, the previous work has largely been limited by the noise level, inadequate dynamic range and frequency response of then-available sound detection and recording apparatus.